The tried and true good stuff that feels as if it is in the same universe as the films; chiefly the Daley Han Solo trilogy, the Thrawn trilogy, Splinter of the Mind's Eye, Jedi Apprentice and the better of the 90's Bantam era.
Toss out the NJO crud. (I still need to try this again and get through NJO onwards.)
But the more simple answer...
Mara Jade.
Done.
Can we just have a Mara movie? Or another book? Or anything?
Pleeeease?